Radial cages, or needle roller and cage assemblies including radial cages, are well suited for high rotational speeds. Such assemblies are often used in planetary transmissions, which due to the high rotational speeds at which they operate, place high demands on the installed needle roller and cage assemblies. Needle roller and cage assemblies of this type usually include a radial cage and of a plurality of needle rollers received in the radial cage and are distinguished in particular by a smallest-possible radial installation height. At the same time, however, needle roller and cage assemblies can absorb high centrifugal forces and high acceleration forces and thus have a high load-bearing capacity and a high running accuracy.
A radial cage for a needle roller and cage assembly of this type is usually comprised of two side rings defining an axial extension of the radial cage. A plurality of generally axial bridges connect these side rings to each other, which axial bridges form or define pockets for receiving the needle rollers. In order to achieve low cage distortion or deformation even at high rotational speeds, the axial bridges are each formed by two axially straight side sections connected to the side rings, and by two intermediate sections extending obliquely with respect to the cage longitudinal axis, and by an axial center section. This stepped design is intended to reduce the effect of centrifugal forces on the cage and makes it possible for the needle rollers to be held by the axial bridges in the radial cage.
Disadvantageously, however, at very high rotational speeds, the bridges of these cages may break in the region of the straight side sections of the axial bridges. This is because the radial cage is stressed by the intermittent extremely high centrifugal forces such that the axial bridges bend radially outward due to their own mass. This deformation in turn leads to an undesired contact between radial cage and needle rollers, which in turn results in an increase in friction and a removal of the lubricant film. The service life and durability of the bearing are thereby significantly reduced. In addition, in particular when additional axial loads are applied to the bearing, the required low installation height can lead to the necessarily thin needle rollers being overrolled from the bearing cage into the region of the side rings. This can cause a total failure of the bearing.